1. Field of the Invention
The present invention relates to torsional vibration dampers, and in particular to an arrangement for a torsional vibration damper in a clutch disk.
2. Description of the Related Art
A torsional vibration damper of this type is known, for example, from DE 195 45 973 C1. In said known torsional vibration damper, a hub disk meshes with a hub element, thus permitting a predetermined free angle of rotation between the hub disk and the hub element. Acting between the hub disk and the hub element, and arranged on one side of the hub disk, is a damping arrangement of an idling damper. Furthermore, covering-disk elements are arranged respectively on each axial side of the hub disk. The two covering-disk elements and the hub disk form respective transmission arrangements of a load damper. Acting between said two transmission arrangements, i.e. the two covering-disk elements on the one hand and the hub disk on the other hand, is a further damping arrangement in the form of damping springs. The hub disk, the covering-disk elements and the idling damper or components thereof form a hub-disk arrangement which is mounted on the hub element via a bearing ring. For this purpose, the hub ring has a conical bearing surface which rests against a bearing surface of complementary shape on the hub element. Here the bearing ring is supported in the axial direction on one of the covering-disk elements. Acting between the hub element and the other one of the covering-disk elements is a prestressing spring, which braces the bearing ring between the first-mentioned covering-disk element and the hub element. Furthermore, in this torsional vibration damper, a friction device is provided, which becomes active whenever a relative rotation between the two transmission arrangements occurs. This friction device comprises a friction element which is clamped between one of the covering-disk elements and a component which is fixed against rotation to the hub disk. In order to clamp the friction element between the two components mentioned a prestressing force is generated by means of a second spring arrangement in the form of a corrugated washer.
In this known torsional vibration damper, there are therefore two spring arrangements which, independently of one another, provide the prestressing force for the axial prestressing of the entire hub-disk arrangement in relation to the hub element and the prestressing force to generate the friction damping force. On account of the various functions, i.e. centering by means of the bearing ring, generation of the frictional force in the main damper stage and generation of respective prestressing forces, this torsional vibration damper has a large number of parts which make the construction complicated and cost-intensive.
A clutch disk is known from DE 33 13 850 A1, which likewise has an idling damper stage and a load damper stage. The idling damper stage is formed by a damping spring arrangement which acts between a flange, projecting radially from the hub element, and a hub disk which surrounds the flange on both sides in the axial direction. A second second damping spring arrangement then acts between said hub disk and covering-disk elements arranged in the axial direction on both sides of the hub disk. The axial centering of the hub-disk arrangement constructed in this manner is provided by a bearing ring which lies between the flange provided on the hub element, and a disk-like section of the hub disk. A prestressing spring acts between the flange and the other disk-like section of the hub disk located on the other axial side of the flange to produce a prestressing force for the axial bearing. Furthermore, a friction device for the load damper stage is provided, which comprises a friction ring, located between one of the covering-disk elements and the disk-like region of the hub disk adjacent to said covering-disk element, and a prestressing spring which acts between the friction ring and said disk-like region of the hub disk. This arrangement also generated the prestressing forces for the axial centering and for the generation of frictional force in the load damper stage using separate prestressing springs which each act on different components, i.e. bearing or friction rings.